High-entropy titanate pyrochlore as newly low-thermal conductivity ceramics

Low-thermal conductivity ceramics play an indispensable role in maximizing the efficiency and durability of hot end components. Pyrochlore, particularly zirconate pyrochlore, is currently a highly promising and widely studied candidate for its extremely low thermal conductivity. However, there are still few pyrochlores that offer both stiffness, insulation, and good thermal expansion properties. In this work, the solidification method was innovatively introduced into the preparation of titanate pyrochlore, and combined it with the compositional design of high-entropy. Through careful composition design and solidification control, the high-density and uniform elements distributed high-entropy titanate pyrochlore ceramics were successfully prepared. These samples possess high hardness (15.88 GPa) and Young’s modulus (295.5 GPa), low thermal conductivity (0.947 W·m −1 ·K −1 ), excellent thermal expansion coefficient (11.6 ×10 −6 /K) and an exquisite balance between stiffness and insulation (E/κ, 312.1 GPa·W −1 ·m·K), in which the E/κ exhibits the highest value among the current reported works. • Propose a new synthesis way for high-entropy ceramics by melt solidification. • Samples possess a record-breaking balance between stiffness and insulation (E/κ). • The obtained ceramics exhibit extremely low thermal conductivity and high hardness.